1. Field of the Invention
This invention relates to films useful for blocking infrared (IR) and/or near infra red (NIR) light. This invention particularly relates to polymers having IR and/or NIR-blocking coatings on at least a portion of their surface and to a process for preparing same.
2. Description of the Related Art
Several patents and publications are cited in this description in order to more fully describe the state of the art to which this invention pertains. The entire disclosure of each of these patents and publications is incorporated by reference herein.
There is growing interest in means of controlling solar heat gain in automobiles and buildings. Various coated glasses have been proposed to reduce solar heat gain through windows. These coatings, however, which are generally thin films of silver or other metallic compounds, also generally block out electromotive energy. This effect renders inoperative various modern necessities such as cell phones, global positioning satellite (GPS) units, and automatic toll takers on toll roads. It has been demonstrated, however, that electromotive energy can pass through treated windows when the blocking particles are well separated from one another.
Coatings comprising dispersed blocking particles and disposed on glass or other substrates are well known. See, for example, U.S. Pat. Nos. 5,518,810; 6,579,608; and 6,506,487. These particles can include UV absorbing compounds, visible colored pigments, NIR (heat) absorbing compounds, or any combination of these entities. However, the energy blocking coatings known in the art generally have poor adhesion to some polymeric surfaces, particularly polyvinyl butyral (PVB). Good adhesion between the polymer interlayer and both the energy blocking coating and the glass are necessary requirements for appropriate functionality in a laminated safety glass. Adhesion that is too low can lead to exfoliation of the safety glass laminates, while adhesion that is too high can lead to impact failures.